The present invention relates to a high pressure fluid system and more particularly to advancements in the safety, maintenance and servicing of the same.
High pressure fluid jetting systems are used in a variety of fluid jetting operations, such as cleaning, pipe clearing, cutting, removal of debris and coating, to name a few. Most such systems include a fluid end assembly, a drive assembly, a pressurized liquid supply and water blasting equipment, such as a spray gun. The drive assembly usually is in the form of an engine or motor coupled to a drive shaft that drives multiple plungers in a reciprocating manner within a fluid cylinder end. The multiple plungers force fluid, such as water, out of the spray gun at extremely high pressure. As the plungers reciprocate, the fluid cylinder assembly and its components cycle at an extremely high rate and fluctuate between atmospheric and maximum system pressure.
Because of the operation between high and low pressures, and the high rate of operation components of the fluid end assembly undergo extreme stress and wear. Typically, the high wear components of such an assembly or system are mounted deep within a fluid cylinder end, and are hard to access. This makes replacement and general service of these high wear components difficult and time consuming Some service jobs take several hours to a full day, which means that the system is out of commission for extended durations. This can be very costly, particularly where the system is being used to clean a plant or facility that is off-line while the cleaning takes place.
To understand the difficulty of servicing conventional fluid end assemblies, one may look to their complexity. Most fluid end assemblies include a manifold that bolts to a frame with multiple bolts that extend through the entire assembly. To access and service the high wear components, such as a valve seat assembly and seal cartridge (or stuffing box) within the assembly, the multiple bolts (twelve or more) must be removed, so the manifold can be detached from the frame. The manifold itself weighs several hundred pounds, so its handling can be difficult alone. After the manifold is removed—which can be a several hour chore—the primary internal components can be accessed and serviced or replaced. After that is done, the unwieldy manifold then must be re-mounted to the frame, with the multiple bolts carefully tightened to a precise torque to ensure the assembly does not leak or fail. Thus, the servicing of conventional fluid end assemblies is extremely time consuming and difficult.
As mentioned above, the removable manifolds of fluid end assemblies are large and unwieldy. They also can present several other issues. For example, manifolds usually include a single discharge port which feeds to the water blasting equipment, such as a spray gun. The discharge port usually dictates the output of the manifold, and thus the fluid end assembly. With only one discharge port per manifold, customization is limited, and can require replacement of the entire manifold to provide variability. Further, the discharge port and end of the hose, to which the water blasting equipment is attached, are both threaded. Sometimes, the threads can become stripped or damaged due to careless handling or galling, in which case the entire manifold may need to be replaced or the port rethreaded. This can be extremely costly and time consuming.
Most fluid end assemblies include a rupture disc mounted in the manifold to provide protection against excessive pressure build-up in the water blasting equipment attached to the system. The rupture disc is carefully selected to match the output of the system and avoid a dangerous condition. For example, where a fluid end assembly is designed to output 10,000 psi (about 40 gpm), a 10,000 psi rupture disc matching that output should be installed to prevent over-pressurization of the system. If, instead, a rupture disc designed for a 40,000 psi (about 10 gpm) is erroneously used, the system could be over-pressurized and could fail, which could lead to great bodily injury to an operator of the blasting equipment or worse. During field service of the rupture disc, operator error in selecting the wrong rupture disc is frequently increased due to time, pressure and a sensory overloading environment.
Almost all modern fluid end assemblies include a collet connection between the plungers of the fluid end assembly and a cross-head stub in a power frame. The collet includes a collar and a forcing cone. The collar is tightened and untightened with a wrench to ensure the connection is secure between the elements. While this is a workable connection, it is time consuming and requires the use of an extra hand tool to service the connection.
As mentioned above, conventional fluid end assemblies operate at high rates, pressures and cycle times. Thus, the assemblies typically include lubricating or cooling plumbing to cool/lubricate the components. As an example, a plunger is lubricated with water via an intricate system of external hoses and valves coupled to a separate system designated to circulate liquid to the seal cartridge assembly, and in particular, the packing and the plunger. During service of the fluid end assembly, the external plumbing hoses and valves usually are disconnected and removed before access to the high wear components, such as the packing and plunger, can be achieved. This extra step involving the plumbing then is reversed upon re-assembly of the fluid end assembly. The uncoupling and re-coupling of these components is time consuming and can lead to system failure if improperly executed.
While conventional fluid end assemblies offer some level of serviceability and safety, some can fall short, and can present complex operation and servicing issues.